A year after getting the scope and having failed to
achieve acceptable collimation, I'm starting over.

Checking the secondary tilt with a single beam laser,
it was clear that the beam did not return on itself, and
thus the secondary mirror was misaligned. (What you see here
is the reflection on the primary mirror of the secondary mirror,
and that mirror's reflection of the laser in the focuser).
It took about 3/4 of a turn on the collimation bolts to bring
the two laser dots (the light exiting the laser and the beam reflected
back by the secondary mirror) onto each other.